Method for electrochemical production of a crystalline porous metal organic skeleton material

ABSTRACT

A method of electrochemically preparing a crystalline, porous, metal-organic framework material comprising at least one at least bidentate organic compound coordinately bound to at least one metal ion, in a reaction medium comprising the at least one bidentate organic compound, wherein at least one metal ion is provided in the reaction medium by the oxidation of one anode comprising the corresponding metal.

This application is a divisional application of U.S. application Ser.No. 10/580,407, filed on May 24, 2006, which is a 371 of PCT/EP04/13236,filed on Nov. 22, 2004, and claims priority to German Patent ApplicationNo. 103 55 087.9, filed on Nov. 24, 2003.

The present invention relates to a method of electrochemically preparinga crystalline, porous, metal-organic framework material. In the scope ofthis method, the metal ion present in the framework material is providedat least in part via anodic oxidation. The present invention alsorelates to the inventively prepared framework material per se and topreferred uses, for example as a storage medium for liquids and gases.

Crystalline, porous, metal-organic framework materials, so-called“metal-organic frameworks” (MOF) having specific pores or poredistributions and large specific surface areas have been the subject,particularly most recently, of extensive research activities.

For example, U.S. Pat. No. 5,648,508 describes microporous,metal-organic materials which are prepared under mild reactionconditions from a metal ion and a ligand in the presence of a templatecompound.

WO 02/088148 discloses the preparation of a series of compounds havingthe same framework topology. These so-called IMOF (IsoreticularMetal-Organic Framework) structures represent monocrystalline andmesoporous framework materials having a very high storage capacity forgases.

Eddaoudi et al., Science, 295 (2002) p. 469-472, for example describesthe preparation of a so-called MOF-5, the starting material being a zincsalt, i.e. zinc nitrate, the synthesis of the MOF involving dissolvingthis salt and 1,4-benzenedicarboxylic acid (BDC) inN,N′-diethylformamide (DEF).

Chen et al., Science, 291 (2001) p. 1021-1023, for example describes thepreparation of a so-called MOF-14, the starting material being a coppersalt, i.e. copper nitrate, the synthesis of the MOF involving dissolvingthis salt and 4,4′,4″-benzene-1,3,5-triyltribenzoic acid (H₃BTC) inN,N′-dimethylformamide (DMF) and water.

Accordingly, in all the methods described in the prior art of preparingthese porous, metal-organic framework materials, the metal ion to whichthe ligands are coordinatively bound is provided via a correspondingmetal salt solution, in each case a solution which comprises thedissolved metal salt being brought into contact with a ligand in thepresence of a suitable template compound.

This procedure does entail serious safety problems since, for example,the preparation of copper-containing metal-organic framework materialsin many cases involves the presence in the solution, besides copperions, of nitrate anions which are introduced into the reaction systemvia the copper salt. The synthesis then results in large-surface-areametal complexes in concentrated, nitrate-containing phases, the phasesadditionally comprising organic solvents. Such phases, when overheated,can have a tendency to decompose spontaneously. If, on the other hand,as likewise described in the prior art in many cases, a solution on thebasis of halides is used instead of a nitrate-containing metal saltsolution, this will result, in industrial applications, in the rapidcorrosion of apparatus components, thus requiring expensivecorrosion-resistant materials.

One of the objects of the present invention therefore was to provide amethod which does not have these drawbacks.

We have found that this object is achieved by a method based on anentirely different approach, in which the metal ion to which the ligandof the framework material is coordinatively bound is provided not via ametal salt but via an electrochemical route. In the scope of the presentinvention, the introduction of the at least one metal ion in themetal-organic framework material into the reaction system is thereforeeffected, at least in part, via anodic oxidation.

Accordingly, the present invention relates to a method ofelectrochemically preparing a crystalline, porous, metal-organicframework material comprising at least one at least bidentate organiccompound coordinately bound to at least one metal ion, in a reactionmedium comprising the at least one bidentate organic compound, whereinat least one metal ion is provided in the reaction medium by theoxidation of at least one anode comprising the corresponding metal.

The term “electrochemical preparation” as employed within the scope ofthe present invention relates to a preparation method in which theformation of at least one reaction product is attendant on the migrationof electrical charges or the occurrence of electrical potentials.

The term “at least one metal ion” as used within the scope of thepresent invention relates to embodiments according to which at least oneion of a metal or at least one ion of a first metal and at least one ionof at least one second metal differing from the first metal are providedby anodic oxidation.

Accordingly, the present invention comprises embodiments in which atleast one ion of at least one metal is provided via anodic oxidation andat least one ion of at least one metal is provided via a metal salt,where the at least one metal in the metal salt and the at least onemetal provided via anodic oxidation as a metal ion can be identical ordifferent from one another. The present invention therefore comprises,for example, an embodiment according to which the reaction mediumcomprises one or more different salts of a metal and the metal ionpresent in this salt or these salts is additionally provided via anodicoxidation of at least one anode comprising said metal. Likewise, thepresent invention comprises an embodiment according to which thereaction medium comprises one or more different salts of at least onemetal and at least one metal different from these metals is provided viaanodic oxidation as a metal ion in the reaction medium.

According to a preferred embodiment of the present invention, the atleast one metal ion is provided via anodic oxidation of at least oneanode comprising said at least one metal, no further metal beingprovided via a metal salt.

Accordingly, the present invention comprises an embodiment, according towhich the at least one anode comprises a single metal or two or moremetals, in the case of the anode comprising a single metal, said metalbeing provided by anodic oxidation, and in the case of the anodecomprising two or more metals, at least one of said metals beingprovided via anodic oxidation.

The present invention further comprises an embodiment according to whichat least two anodes are used, these two being optionally identical ordifferent. Each of the at least two anodes in this arrangement cancomprise a single metal or two or more metals. In this context it ispossible, for example, for two different anodes to comprise the samemetals, but in different proportions. Equally it is possible, forexample, in the case of different anodes for a first anode to comprise afirst metal and a second anode to comprise a second metal, the firstanode not comprising the second metal and/or the second anode notcomprising the first metal.

The term “metal” as used within the scope of the present inventioncomprises all those elements of the Periodic Table of the Elements whichcan be provided in a reaction medium via anodic oxidation via anelectrochemical route and are able to form at least one metal-organic,porous framework material with at least one at least bidentate organiccompound.

Especially preferred in the scope of the present invention are elementsof groups Ia, IIa, IIIa, IVa to VIIIa and Ib and VIb of the periodictable of the elements. These preferred elements include Mg, Ca, Sr, Ba,Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir,Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As,Sb and Bi. More preferred are Zn, Cu, Ni, Pd, Pt, Ru, Rh, Fe, Mn, Ag andCo. Greater preference within the scope of the present invention isgiven to Cu, Fe, Co, Zn, Mn and Ag. Especially preferred are Cu, Fe andZn.

Among metal ions provided via anodic oxidation in the reaction medium,Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti⁴⁺, Zr⁴⁺, Hf⁴⁺, V⁴⁺, V³⁺, V²⁺,Nb³⁺, Ta³⁺, Cr³⁺, Mo³⁺, W³⁺, Mn³⁺, Mn²⁺, Re³⁺, Re²⁺, Fe³⁺, Fe²⁺, Ru³⁺,Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺, Rh²⁺, Rh⁺, Ir²⁺, Ir⁺, Ni²⁺, Ni⁺, Pd²⁺,Pd⁺, Pt²⁺, Pt⁺, Cu²⁺, Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ga³⁺, In³⁺,Ti³⁺, Si⁴⁺, Si²⁺, Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, As⁵⁺, As³⁺, As⁺,Sb⁵⁺, Sb³⁺, Sb⁺, Bi⁵⁺, Bi³⁺ and Bi⁺ can be mentioned in particular.Particularly preferred are Cu²⁺, Cu⁺, Fe²⁺, Fe³⁺, Zn²⁺, Co³⁺, Co²⁺, Ag⁺,Mg²⁺ and Mn²⁺. Especially preferred are Cu²⁺, Cu⁺, Fe²⁺; Fe³⁺ and Zn²⁺.

Accordingly, the present invention also describes a method as describedabove, wherein the metal ion source used is a copper- and/or an iron-and/or a zinc- and/or a silver- and/or a manganese-comprising anode.

Likewise, the present invention also describes a method as describedabove, wherein the metal ion source used is a copper- and/or an iron-and/or a zinc- and/or a manganese-comprising anode.

According to a preferred embodiment, the present invention also relatesto a method as described above, wherein the metal ion source used is acopper- and/or an iron- and/or a zinc-comprising anode.

The configuration of the anode employed in the method according to theinvention can in principle be chosen at will, as long as the ability toprovide the at least one metal ion in the reaction medium via anodicoxidation to form the porous, metal-organic framework material isensured.

Preferred, inter alia are anodes in the form of a rod and/or an annulusand/or a disk such as, for example, an annular disk and/or a plateand/or a tube and/or a bed and/or a cylinder and/or a cone and/or atruncated cone.

According to a preferred embodiment, the method according to theinvention is implemented employing at least one sacrificial anode. Theterm “sacrificial anode” as used within the scope of the presentinvention refers to an anode which in the course of the inventive methoddissolves, at least in part. This also includes embodiments in which atleast part of the dissolved anode material is replaced in the course ofthe process. This can be effected, for example, by at least one newanode being introduced into the reaction system or, according to apreferred embodiment, an anode being introduced into the reaction systemand in the course of the inventive method being fed forward continuouslyor discontinuously into the reaction system.

The method according to the invention preferably makes use of anodeswhich consist of the at least one metal serving as the metal ion sourceor which comprise said at least one metal applied to at least onesuitable support material.

The geometry of the at least one support material is essentially notsubject to any restrictions. Possible options include, for example, theuse of support materials in the form of a fabric and/or a sheet and/or afelt and/or a screen and/or rod and/or a cartridge and/or a cone and/ora truncated cone and/or an annulus and/or a disk and/or a plate and/or atube and/or a bed and/or a cylinder.

Potentially suitable support materials according to the inventioninclude, for example, metals such as e.g. at least one of theabovementioned metals, alloys such as e.g. steels or bronzes or brass,graphite, felt or foams.

Most especially preferred are anodes which consist of the at least onemetal serving as the metal ion source.

The configuration of the cathode employed in the method according to theinvention can in principle be chosen at will, as long as the ability toprovide the at least one metal ion in the reaction medium via anodicoxidation to form the porous, metal-organic framework material isensured.

According to a preferred embodiment of the method according to theinvention, the electroconductive electrode material of the at least onecathode is selected so as to ensure that no troublesome side reactiontakes place in the reaction medium. Cathode materials preferred interalia include, inter alia, graphite, copper, zinc, tin, manganese,silver, gold, platinum or alloys such as e.g. steels, bronzes or brass.

Examples of combinations preferred inter alia of the anode materialserving as the metal ion source and of the electroconductive cathodematerial include:

Anode Cathode Zinc Zinc Copper Copper Magnesium Copper Cobalt CobaltIron Steel Copper Steel

The geometry of the at least one cathode is essentially subject to norestrictions. Possible options include, for example, the use of cathodesin the form of a rod and/or an annulus and/or a disk and/or a plateand/or a tube.

Within the scope of the present invention, essentially any cell typecustomarily used in electrochemistry can be employed. Most especiallypreferred in the method according to the invention is an electrolyticcell suitable for the use of sacrificial electrodes.

In principle it is possible, inter alia, to employ split cells with, forexample, a plan parallel electrode arrangement or cartridge-typeelectrodes. The separation medium used between the cell compartmentscan, for example, be ion exchange membranes, microporous membranes,diaphragms, filter fabrics from electron-nonconducting materials, glassfrits and/or porous ceramic materials. Preference is given to the use ofion exchange membranes, particularly cation exchange membranes,preference among these being given in turn to those membranes whichcomprise a copolymer of tetrafluoroethylene and a perfluorinated monomercomprising sulfonic acid groups.

Within the scope of a preferred embodiment of the method according tothe invention, preference is given to the use of one or more undividedcells.

Accordingly, the present invention also relates to a method as describedabove which is implemented in an undivided electrolytic cell.

Most especially preferred are combinations of geometries of anode andcathode in which those sides of the anode and cathode which face oneanother jointly form a gap of homogeneous thickness.

In the at least one undivided cell, the electrodes are, for example,preferably arranged plan parallel, the electrode gap having ahomogeneous thickness, for example, in the range of from 0.5 mm to 30mm, preferably in the range of from 0.75 mm to 20 mm and particularlypreferably in the range of from 1 to 10 mm.

Within the scope of a preferred embodiment it is possible for example,for a cathode and an anode to be arranged plan parallel in such a waythat in the resulting cell an electrode gap is formed having ahomogeneous thickness in the range of from 0.5 to 30 mm, preferably inthe range of from 1 to 20 mm, more preferably in the range of from 5 to15 mm and particularly preferably in the range of from 8 to 12 mm, forexample in the range of about 10 mm. This type of cell is referred to,within the scope of the present invention, by the term “gap cell”.

According to a preferred embodiment of the method according to theinvention, the above-described cell is employed as a cell connected forbipolar operation.

In addition to the above-described cell, a likewise preferred embodimentwithin the scope of the method according to the invention employs theelectrodes singly or a plurality of them stacked on top of one another.In the latter case, these are so-called stack electrodes which arepreferably serially connected for bipolar operation in the accordinglyso-called plate stack cell. Particularly when the method according tothe invention is implemented on an industrial scale, preferably at leastone cup cell and particularly preferably plate stack cells connected inseries are used, whose fundamental configuration is described in DE 19533 773 A1 which is incorporated by reference.

Within the scope of the preferred embodiment of the plate stack cell, itis preferred, for example, for disks of suitable materials such as e.g.copper disks to be arranged in a plan parallel manner in such a waythat, between the individual disks in each case, a gap is formed havinga homogeneous thickness in the range of from 0.5 to 30 mm, preferably inthe range of from 0.6 to 20 mm, more preferably in the range of from 0.7to 10 mm, more preferably in the range of from 0.8 to 5 mm andparticularly in the range of from 0.9 to 2 mm, for example in the rangeof about 1 mm. In this arrangement, the spacings between the individualdisks can be identical or different, the spacings between the disksaccording to a particularly preferred embodiment being essentiallyequal. According to a further embodiment, the material of one disk ofthe plate stack cell can differ from the material of another disk of theplate stack cell. For example, one disk can be made of graphite, anotherdisk made of copper, the copper disk preferably being connected as theanode and the graphite disk preferably being connected as the cathode.

It is also preferred, for example, within the scope of the presentinvention to use so-called “pencil sharpener” cells as described, forexample, in J. Chaussard et al., J. Appl. Electrochem. 19 (1989)345-348, which is incorporated by reference. Particular preference isgiven in the method according to the invention to pencil sharpenerelectrodes having rod-shaped feed electrodes.

In particular, the present invention accordingly also relates to amethod as described above which is implemented in a gap cell or platestack cell.

Cells in which the electrode gap is in the range of less than or equalto 1 mm are referred to as capillary gap cells.

According to likewise preferred embodiments of the method according tothe invention, electrolytic cells can be used which, for example, haveporous electrodes comprising metal beds or, for example, have porouselectrodes comprising metal meshes or, for example, have electrodescomprising both metal beds and metal meshes.

According to a further preferred embodiment, the method according to theinvention makes use of electrolytic cells which have at least onesacrificial anode of round, disk-shaped cross section and at least onecathode of annular cross section, the diameter of the preferablycylindrical anode particularly preferably being smaller than theinternal diameter of the cathode, and the anode being disposed in such away within the cathode that a gap of homogeneous thickness is formedbetween the outer face of the cylindrical shell of the anode and theinner face of the cathode which at least partially surrounds the anode.

Within the scope of the present invention it is also possible to reversepolarity and thus convert the original anode into the cathode and theoriginal cathode into the anode. Within the scope of this variant of themethod it is possible, for example, if electrodes comprising differentmetals are suitably selected, to provide first one metal via anodicoxidation as the metal cation to build up the metal-organic frameworkmaterial and, in a second step after polarity reversal, to provide asecond metal to build up the metal-organic framework material. It isalso possible to effect polarity reversal by applying an AC current.

In principle it is possible for the method to be implemented in batchmode or continuously or in mixed-mode operation. Preferably, the methodis implemented continuously in at least one flow cell.

The voltages employed in the method according to the invention can beadapted to the at least one metal which is present in the at least oneanode and serves as the metal ion source for the porous, metal-organicframework material and/or to the properties of the at least onebidentate organic compound and/or if appropriate to the properties ofthe below-described at least one solvent and/or if appropriate to theproperties of the below-described at least one conducting salt and/or tothe properties of the below-described at least one cathodicdepolarization compound.

In general, the voltages per electrode pair are in the range of from 0.5to 100 V, preferably in the range of from 2 to 40 V, particularlypreferably in the range of from 4 to 20 V. Examples of preferred rangesare from 4 to 10 V or from 10 to 20 V or from 20 to 25 V or from 10 to25 V or from 4 to 20 V or from 4 to 25 V. In this context, the voltagecan be constant during the inventive method or can change continuouslyor discontinuously in the course of the method.

In the case, for example, of copper being oxidized anodically, thevoltages are generally in the range of from 3 to 20 V, preferably in therange of from 3.5 to 15 V and particularly preferably in the range offrom 4 to 15 V.

The current densities which occur within the scope of the inventivepreparation of the porous, organic framework materials are generally inthe range of from 0.01 to 1000 mA/cm², preferably in the range of from0.1 to 1000 mA/cm², more preferably in the range of from 0.2 to 200mA/cm², more preferably in the range of from 0.3 to 100 mA/cm² andparticularly preferably in the range of from 0.5 to 50 mA/cm².

The quantities of electricity (Ah) employed in the method according tothe invention are preferably in the range of from 30 to 200% of thequantity of electricity required to neutralize the amount of thepreferably employed acid equivalence of the at least one at leastbidentate compound.

The method according to the invention is generally implemented at atemperature in the range of from 0° C. up to a boiling point, preferablyin the range of from 20° C. up to the boiling point of the reactionmedium in question or of the at least one solvent employed, preferablyat atmospheric pressure. Equally it is possible to implement the methodunder pressure, pressure and temperature preferably being chosen suchthat the reaction medium is preferably at least partially liquid.

In general, the method according to the invention is implemented at apressure in the range of from 0.5 to 50 bar, preferably in the range offrom 1 to 6 bar and particularly preferably at atmospheric pressure.

Depending on type and state of aggregation of the components of thereaction medium, the electrochemical preparation according to theinvention of the porous, metal-organic framework material can inprinciple also be carried out without an additional solvent. This isparticularly the case, for example, if at least one of the at leastbidentate compounds in the reaction medium acts as a solvent or solventmixture.

Equally it is possible, in principle, without employing a solvent toimplement the method according to the invention, for example, in themelt, at least one component of the reaction medium being present in themolten state.

According to a preferred embodiment of the present invention, thereaction medium comprises at least one suitable solvent in addition tothe at least one at least bidentate organic compound and the optional atleast one conducting salt and the optional at least one cathodicdepolarization compound. In that case, the chemical nature and theamount of said at least one solvent can be adapted to the at least oneat least bidentate organic compound and/or to the at least oneconducting salt and/or to the at least one cathodic depolarizationcompound and/or to the at least one metal ion.

Accordingly, the present invention also describes a method as describedabove, wherein the reaction medium, in addition to the at least one atleast bidentate organic compound, additionally comprises at least onesolvent.

Conceivable in principle as the solvent are all solvents or all solventmixtures in which the starting materials employed in the method can beat least partially dissolved or suspended under the reaction conditionschosen such as pressure and temperature. Examples of preferentially usedsolvents include inter alia

-   -   water;    -   alcohols having 1, 2, 3 or 4 carbon atoms such as methanol,        ethanol, n-propanol, isopropanol, n-butanol, isobutanol,        t-butanol;    -   carboxylic acids having 1, 2, 3 or 4 carbon atoms such as formic        acid, acidic acid, propionic acid or butanoic acid;    -   nitriles such as e.g. acetonitrile or cyanobenzene;    -   ketones such as e.g. acetone;    -   at least singly halogen-substituted low-molecular-weight alkanes        such as e.g. methylene chloride or 1,2-dichloroethane;    -   acid amides such as e.g. amides of low-molecular-weight        carboxylic acids such as e.g. carboxylic acids having 1, 2, 3 or        4 carbon atoms such as amides of formic acid, acetic acid,        propionic acid or butanoic acid such as e.g. formamide,        dimethylformamide (DMF), diethylformamide (DEF),        t-butylformamide, acetamide, dimethylacetamide, diethylacetamide        or t-butylacetamide;    -   cyclic ethers such as e.g. tetrahydrofuran or dioxane;    -   N-formylamides or N-acetylamides or symmetric or asymmetric urea        derivatives of primary, secondary or cyclic amines such as e.g.        ethylamine, diethylamine, piperidine or morpholine;    -   amines such as e.g. ethanolamine, triethylamine or        ethylenediamine;    -   dimethyl sulfoxide;    -   pyridine;    -   trialkyl phosphites and phosphates;        or mixtures of two or more of the abovementioned compounds.

The term “solvents” as used above includes both pure solvents andsolvents comprising, in small amounts, at least one further compound,for example preferably water. In this case, the water contents of theabovementioned solvents are in the range of up to 1 wt %, preferably inthe range of up to 0.5 wt %, particularly preferably in the range offrom 0.01 to 0.5 wt % and especially preferably in the range of from 0.1to 0.5 wt %. The term “methanol” or “ethanol” or “acetonitrile” or “DMF”or “DEF”, for example, is to be understood, within the scope of thepresent invention, to include a solvent which in each case, particularlypreferably, can comprise water in the range of from 0.1 to 0.5 wt %.

Preferred solvents used in the method according to the invention aremethanol, ethanol, acetonitrile, DMF and DEF or mixtures of two or moreof these compounds. Most especially preferred solvents are methanol,ethanol, DMF, DEF and mixtures of two or more of these compounds.

Within the scope of a preferred embodiment, the solvent used comprisesat least one protic solvent. This is preferentially employed, interalia, in those cases where, to avoid the below-described redeposition,on the cathode, of the at least one metal ion provided by anodicoxidation, the cathodic generation of hydrogen is to be effected.

If, for example, methanol is used as the solvent, the temperature in themethod according to the invention at atmospheric pressure is generallyin the range of from 0 to 90° C.; preferably in the range of from 0 to65° C. and particularly preferably in the range of from 25 to 65° C.

If, for example, ethanol is used as the solvent, the temperature in themethod according to the invention at atmospheric pressure is generallyin the range of from 0 to 100° C.; preferably in the range of from 0 to78° C. and particularly preferably in the range of from 25 to 78° C.

The pH of the reaction medium in the method according to the inventionis adjusted so as to favor the synthesis or the stability or preferablythe synthesis and the stability of the framework material. For example,the pH can be adjusted via the at least one conducting salt.

If the reaction is carried out as a batch reaction, the reactionduration is generally in the range of up to 30 h, preferably in therange of up to 20 h, more preferably in the range of from 1 to 10 h andparticularly preferably in the range of from 1 to 5 h.

The term “at least bidentate organic compound” as used within the scopeof the present invention refers to an organic compound comprising atleast one functional group which is able to form at least two,preferably two coordinative bonds to a given metal ion and/or to formone coordinative bond each to two or more, preferably two metal atoms.

Examples of functional groups to be mentioned, via which the saidcoordinative bonds can be formed, include the following functionalgroups in particular: —CO₂H, —CS₂H, —NO₂, —B(OH)₂, —SO₃H, —Si(OH)₃,—Ge(OH)₃, —Sn(OH)₃, —Si(SH)₄, —Ge(SH)₄, —Sn(SH)₃, —PO₃H, —AsO₃H, —AsO₄H,—P(SH)₃, —As(SH)₃, —CH(RSH)₂, —C(RSH)₃, —CH(RNH₂)₂, —C(RNH₂)₃,—CH(ROH)₂, —C(ROH)₃, —CH(RCN)₂, —C(RCN)₃, where R, for example, ispreferably an alkylene group having 1, 2, 3, 4 or 5 carbon atoms such ase.g. a methylene, ethylene, n-propylene, i-propylene, n-butylene,i-butylene, t-butylene or n-pentylene group or an aryl group containingone or two aromatic nuclei such as e.g. two C₆ rings which may or maynot be condensed and, independently of one another, can be substitutedin a suitable manner by at least one substituent each, and/or which,independently of one another, can each contain at least one heteroatomsuch as e.g. N, O and/or S. In accordance with likewise preferredembodiments, functional groups should be mentioned in which theabovementioned radical R is not present. To be mentioned among theseare, inter alia, —CH(SH)₂, —C(SH)₃, —CH(NH₂)₂, —C(NH₂)₃, —CH(OH)₂,—C(OH)₃, —CH(CN)₂ or —C(CN)₃.

The at least two functional groups can in principle be bound to anysuitable organic compound, as long as there is the assurance that theorganic compound having these functional groups is capable of formingthe coordinative bond and of producing the framework material.

The organic compounds comprising the at least two functional groups arepreferably derived from a saturated or unsaturated aliphatic compound oran aromatic compound or a compound which is both aliphatic and aromatic.

The aliphatic compound or the aliphatic moiety of the both aliphatic andaromatic compound can be linear and/or branched and/or cyclic, aplurality of cycles per compound also being possible. More preferably,the aliphatic compound or the aliphatic moiety of the both aliphatic andaromatic compound comprises from 1 to 15, more preferably from 1 to 14,more preferably from 1 to 13, more preferably from 1 to 12, morepreferably from 1 to 11 and particularly preferably from 1 to 10 C atomssuch as e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 C atoms. Particularlypreferred in this context are, inter alia, methane, adamantane,acetylene, ethylene or butadiene.

The aromatic compound or the aromatic moiety of the both aromatic andaliphatic compound can have one or alternatively more nuclei such ase.g. 2, 3, 4 or 5 nuclei, with the option of the nuclei being separateand/or at least two nuclei being present in condensed form. Particularlypreferably, the aromatic compound or the aromatic moiety of the bothaliphatic and aromatic compound has 1, 2 or 3 nuclei, one or two nucleibeing especially preferred. Independently of one another, each nucleusof the abovementioned compound may further comprise at least oneheteroatom such as e.g. N, O, S, B, P, Si, Al, preferably N, O and/or S.More preferably, the aromatic compound or the aromatic moiety of theboth aromatic and aliphatic compound comprises one or two C₆ nuclei, thetwo nuclei being either separate or being present in condensed form.Aromatic compounds to be mentioned in particular are benzene,naphthalene and/or biphenyl and/or bipyridyl and/or pyridine.

Examples to be mentioned, inter alia are trans-muconic acid or fumaricacid or phenylenebisacrylic acid.

Examples to be mentioned within the scope of the present invention ofdicarboxylic acids are

1,4-butanedicarboxylic acid, 4-oxopyran-2,6-dicarboxylic acid,1,6-hexanedicarboxylic acid, decanedicarboxylic acid,1,8-heptadecanedicarboxylic acid, 1,9-heptadecanedicarboxylic acid,heptadecanedicarboxylic acid, acetylenedicarboxylic acid,1,2-benzenedicarboxylic acid, 2,3-pyridinedicarboxylic acid,pyridine-2,3-dicarboxylic acid, 1,3-butadiene-1,4-dicarboxylic acid,1,4-benzenedicarboxylic acid, p-benzenedicarboxylic acid,imidazole-2,4-dicarboxylic acid, 2-methylquinoline-3,4-dicarboxylicacid, quinoline-2,4-dicarboxylic acid, quinoxaline-2,3-dicarboxylicacid, 6-chloroquinoxaline-2,3-dicarboxylic acid,4,4′-diaminophenylmethane-3,3′-dicarboxylic acid,quinoline-3,4-dicarboxylic acid,7-chloro-4-hydroxyquinoline-2,8-dicarboxylic acid, diimidedicarboxylicacid, pyridine-2,6-dicarboxylic acid, 2-methylimidazole-4,5-dicarboxylicacid, thiophene-3,4-dicarboxylic acid,2-isopropylimidazole-4,5-dicarboxylic acid,tetrahydropyran-4,4-dicarboxylic acid, perylene-3,9-dicarboxylic acid,perylenedicarboxylic acid, Pluriol E 200-dicarboxylic acid,3,6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylicacid, octanedicarboxylic acid, pentane-3,3-carboxylic acid,4,4′-diamino-1,1′-diphenyl-3,3′-dicarboxylic acid,4,4′-diaminodiphenyl-3,3′-dicarboxylic acid, benzidine-3,3′-dicarboxylicacid, 1,4-bis-(phenylamino)benzene-2,5-dicarboxylic acid,1,1′-dinaphthyl-8,8′-dicarboxylic acid,7-chloro-8-methylquinoline-2,3-dicarboxylic acid,1-anilinoanthraquinone-2,4′-dicarboxylic acid,polytetrahydrofuran-250-dicarboxylic acid,1,4-bis(carboxymethyl)piperazine-2,3-dicarboxylic acid,7-chloroquinoline-3,8-dicarboxylic acid,1-(4-carboxy)phenyl-3-(4-chloro) phenylpyrazoline-4,5-dicarboxylic acid,1,4,5,6,7,7,-hexachloro-5-norbornene-2,3-dicarboxylic acid,phenylindanedicarboxylic acid,1,3-dibenzyl-2-oxoimidazolidine-4,5-dicarboxylic acid,1,4-cyclohexanedicarboxylic acid, naphthalene-1,8-dicarboxylic acid,2-benzoylbenzene-1,3-dicarboxylic acid,1,3-dibenzyl-2-oxoimidazolidine-4,5-cisdicarboxylic acid,2,2′-biquinoline-4,4′-dicarboxylic acid, pyridine-3,4-dicarboxylic acid,3,6,9-trioxaundecanedicarboxylic acid, o-hydroxybenzophenonedicarboxylicacid, Pluriol E 300-dicarboxylic acid, Pluriol E 400-dicarboxylic acid,Pluriol E 600-dicarboxylic acid, pyrazole-3,4-dicarboxylic acid,2,3-pyrazinedicarboxylic acid, 5,6-dimethyl-2,3-pyrazinedicarboxylicacid, 4,4′-diaminodiphenyletherdiimidedicarboxylic acid,4,4′-diaminodiphenylmethanediimidedicarboxylic acid,4,4′-diaminodiphenylsulfonediimidedicarboxylic acid,2,6-naphthalenedicarboxylic acid, 1,3-adamantanedicarboxylic acid,1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid,8-methoxy-2,3-naphthalenedicarboxylic acid,8-nitro-2,3-naphthalenedicarboxylic acid,8-sulfo-2,3-naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylicacid, 2′-3′-diphenyl-p-terphenyl-4,4″-dicarboxylic acid,diphenylether-4,4′-dicarboxylic acid, imidazole-4,5-dicarboxylic acid,4(1H)-oxothiochromene-2,8-dicarboxylic acid,5-t-butyl-1,3-benzenedicarboxylic acid, 7,8-quinolinedicarboxylic acid,4,5-imidazoledicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid,hexatriacontanedicarboxylic acid, tetradecanedicarboxylic acid,1,7-heptanedicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid,pyrazine-2,3-dicarboxylic acid, furan-2,5-dicarboxylic acid,1-nonene-6,9-dicarboxylic acid, eicosenedicarboxylic acid,4,4′-dihydroxydiphenylmethane-3,3′-dicarboxylic acid,1-amino-4-methyl-9,10-dioxo-9,10-dihydroanthracene-2,3-dicarboxylicacid, 2,5-pyridinedicarboxylic acid, cyclohexene-2,3-dicarboxylic acid,2,9-dichlorofluorubin-4,11-dicarboxylic acid,7-chloro-3-methylquinoline-6,8-dicarboxylic acid,2,4-dichlorobenzophenone-2′,5′-dicarboxylic acid,1,3-benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid,1-methylpyrrole-3,4-dicarboxylic acid,1-benzyl-1H-pyrrole-3,4-dicarboxylic acid,anthraquinone-1,5-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid,2-nitrobenzene-1,4-dicarboxylic acid, heptane-1,7-dicarboxylic acid,cyclobutane-1,1-dicarboxylic acid, 1,14-tetradecanedicarboxylic acid,5,6-dehydronorbornane-2,3-dicarboxylic acid or5-ethyl-2,3-pyridinedicarboxylic acid,of tricarboxylic acids are2-hydroxy-1,2,3-propanetricarboxylic acid, 7-chloro-2,3,8-quinolinetricarboxylic acid, 1,2,4-benzenetricarboxylic acid,1,2,4-butanetricarboxylic acid, 2-phosphono-1,2,4-butanetricarboxylicacid, 1,3,5-benzenetricarboxylic acid,1-hydroxy-1,2,3-propanetricarboxylic acid,4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-F]quinoline-2,7,9-tricarboxylicacid, 5-acetyl-3-amino-6-methylbenzene-1,2,4-tricarboxylic acid,3-amino-5-benzoyl-6-methylbenzene-1,2,4-tricarboxylic acid,1,2,3-propanetricarboxylic acid or aurinetricarboxylic acid,or of tetracarboxylic acids are1,1-dioxide-perylo[1,12-BCD]thiophene-3,4,9,10-tetracarboxylic acid,perylenetetracarboxylic acids such as perylene-3,4,9,10-tetracarboxylicacid or perylene-1,12-sulfone-3,4,9,10-tetracarboxylic acid,butanetetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acidor meso-1,2,3,4-butanetetracarboxylic acid,decane-2,4,6,8-tetracarboxylic acid,1,4,7,10,13,16-hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid,1,2,4,5-benzenetetracarboxylic acid, 1,2,11,12-dodecanetetracarboxylicacid, 1,2,5,6-hexanetetracarboxylic acid, 1,2,7,8-octanetetracarboxylicacid, 1,4,5,8-naphthalenetetracarboxylic acid,1,2,9,10-decanetetracarboxylic acid, benzophenonetetracarboxylic acid,3,3′,4,4′-benzophenonetetracarboxylic acid,tetrahydrofurantetracarboxylic acid or cyclopentanetetracarboxylic acidssuch as cyclopentane-1,2,3,4-tetracarboxylic acid.

Most especially preferred within the scope of the present invention isthe use, where suitable, of at least monosubstituted mono-, di-, tri-,tetra- or polynuclear aromatic di, tri- or tetracarboxylic acids, eachof the nuclei optionally comprising at least one heteroatom, where twoor more nuclei may comprise identical or different heteroatoms.Preferred, for example, are mononuclear dicarboxylic acids, mononucleartricarboxylic acids, mononuclear tetracarboxylic acids, dinucleardicarboxylic acids, dinuclear tricarboxylic acids, dinucleartetracarboxylic acids, trinuclear dicarboxylic acids, trinucleartricarboxylic acids, trinuclear tetracarboxylic acids, tetranucleardicarboxylic acids, tetranuclear tricarboxylic acids and/or tetranucleartetracarboxylic acids. Examples of suitable heteroatoms are N, O, S, B,P, Si, Al, preferred heteroatoms in this context being N, S and/or O,Suitable substituents to be mentioned in this respect are, inter alia,—OH, a nitro group, an amino group or an alkyl or alkoxy group.

Accordingly, the present invention also relates to a method as describedabove, wherein the at least bidentate organic compound used is anaromatic di-, tri- and/or tetracarboxylic acid.

Particularly preferred at least bidentate organic compounds used in themethod according to the invention are acetylenedicarboxylic acid (ADC),benzenedicarboxylic acids, naphthalenedicarboxylic acids,biphenyldicarboxylic acids such as e.g. 4,4′-biphenyldicarboxylic acid(BPDC), bipyridinedicarboxylic acids such as e.g.2,2′-bipyridinedicarboxylic acids such as e.g.2,2′-bipyridine-5,5′-dicarboxylic acid, benzenetricarboxylic acids suchas e.g. 1,2,3-benzenetricarboxylic acid or 1,3,5-benzenetricarboxylicacid (BTC), adamantanetetracarboxylic acid (ATC), adamantanedibenzoate(ADB) benzenetribenzoate (BTB), methanetetrabenzoate (MTB),adamantanetetrabenzoate or dihydroxyterephthalic acids such as e.g.2,5-dihydroxyterephthalic acid (DHBDC).

Most especially preferred within the scope of the present invention isthe use of, inter alia, terephthalic acid, 2,5-dihydroxyterephthalicacid, 1,2,3-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acidor 2,2′-bipyridine-5,5′-dicarboxylic acid.

According to an example of a preferred embodiment, the at leastbidentate organic compound used is 1,3,5-benzenetricarboxylic acid. Inthe case where at least one solvent is used, the preferred solvent usedis, for example, methanol or ethanol or methanol and ethanol. Ethanol isparticularly preferred.

According to an example of a further preferred embodiment, the at leastbidentate organic compound used is 1,2,3-benzenetricarboxylic acid. Inthe case where at least one solvent is used, the preferred solvent usedis, for example, methanol or ethanol or methanol and ethanol. Methanolis particularly preferred.

According to an example of a further preferred embodiment, the at leastbidentate organic compound used is terephthalic acid. In the case whereat least one solvent is used, the preferred solvent used is, forexample, dimethylformamide or diethylformamide or dimethylformamide anddiethylformamide. Diethylformamide is particularly preferred.

According to an example of a further preferred embodiment, the at leastbidentate organic compound used is dihydroxyterephthalic acid. In thecase where at least one solvent is used, the preferred solvent used is,for example, dimethylformamide or diethylformamide or dimethylformamideand diethylformamide. Diethylformamide is particularly preferred.

According to an example of a further preferred embodiment, the at leastbidentate organic compound used is naphthalene-2,6-dicarboxylic acid. Inthe case where at least one solvent is used, the preferred solvent usedis, for example, methanol or ethanol or methanol and ethanol. Methanolis particularly preferred.

The at least one at least bidentate compound is employed in aconcentration which generally is in the range of from 0.1 to 30 wt %,preferably in the range of from 0.5 to 20 wt % and particularlypreferably in the range of from 2 to 10 wt %, in each case based on thetotal weight of the reaction system minus the weight of the anode andthe cathode. Accordingly, the term “concentration” in this casecomprises both the amount dissolved in the reaction system and anyamount suspended in the reaction system, of the at least one at leastbidentate compound.

According to a preferred embodiment of the method according to theinvention, the at least one at least bidentate compound is addedcontinuously and/or discontinuously as a function of the progress of theelectrolysis and in particular as a function of the decomposition of theanode or liberation of the at least one metal ion and/or as a functionof the formation of the metal-organic framework material.

The following combinations of metal from which the at least one metalcation is provided by anodic oxidation, at least bidentate compound andsolvent are preferred, for example, within the scope of the presentinvention:

Zn/BDC/DEF; Zn/DHBDC/DEF; Zn/H₂BDC/DMF; Zn/BDC/DMF, MeOH; Zn/H₂BDC/DMF;Zn/4,4′-BP-2,2′-DC/DEF; Zn/2,6-NDC/DEF; Zn/H₃BTB/H₂O, DMF, EtOH;Zn/H₂BDC/DMSO; Zn/1,4-NDC/DMF; ZN/H₃BTB/DMF, EtOH; Zn/H₂BDC/DMF, AN;Zn/H₂BDC/DMSO; Zn/H₂BDC/DMSO, MeOH; Zn/H₂BDC/DMSO, n-propanol;Zn/H₂BDC/NMP; Zn/m-BDC/DMF, AN; Zn/1,4-NDC/DMF, EtOH; Zn/H₂N-BDC/DEF,EtOH; Zn/1,4-NDC/DEF; Zn/2,6-NDC/DEF; Zn/PDC/DEF;Cu/BDC/DEF; Cu/1,3,5-BTC/EtOH; Cu/1,2,3-BTC/MeOH; Cu/H₃BTB/H₂O, DMF,EtOH; Cu/H₂BDC(OH)₂/DMF; Cu/thiophenedicarboxylic acid/DEF;Cu/thiophenedicarboxylic acid/DMF; Cu/thiophenedicarboxylic acid/MeOH:Cu/malonic acid/DMF; Cu/glutaric acid/DMF; Cu/tartaric acid/DMF;Fe/H₂BDC/DMF; Fe/H₃BDC/DMF; Fe/BTC/DMF; Fe/BDC/DMF, EtOH; Fe/BPDC/DMF,n-propanol; Fe/m-BDC/pyridine; Fe/m-BDC/DMF, pyridine;Co/BDC/MeOH; Co/H₂BDC/NMP; Co/H₂BDC/DMFMg/BDC/DEF; Mg/BDC(OH)₂/DMF;Pb/H₂BDC/DMF, EtOH;

The meaning of the abbreviations is as follows:

BDC benzenedicarboxylic acid

m-BDC m-benzenedicarboxylic acid

H₂BDC dihydroterephthalic acid

H₂N-BDC aminoterephthalic acid

4,4′-BP-2,2′-DC 4,4′-biphenyl-2,2′-dicarboxylic acid

4,4′-BPDC 4,4′-biphenyldicarboxylic acid

H₃BTB benzene tribenzoate

1,3,5-BTC 1,3,5-benzenetricarboxylic acid

1,2,3-BTC 1,2,3-benzenetricarboxylic acid

DHBDC 2,5-dihydroxyterephthalic acid

2,6-NDC 2,6-naphthalenedicarboxylic acid

1,4-NDC 1,4-naphthalenedicarboxylic acid

PDC pyrenedicarboxylic acid

According to an especially preferred embodiment of the method accordingto the invention, the reaction medium comprises at least one suitableconducting salt. Depending on the at least one at least bidentatecompound used and/or the if appropriate used solvent it is alsopossible, in the method according to the invention, to carry out thepreparation of the metal-organic framework material without anadditional conducting salt.

With respect to the conducting salts which can be used in the methodaccording to the invention there are essentially no restrictions.Preferential use is made, for example, of salts of mineral acids,sulfonic acids, phosphonic acids, boronic acids, alkoxysulfonic acids orcarboxylic acids or of other acidic compounds such as e.g. sulfonic acidamides or imides.

Possible anionic components of the at least one conducting saltaccordingly are, inter alia, sulfate, nitrate, nitrite, sulfite,disulfite, phosphate, hydrogen phosphate, dihydrogen phosphate,diphosphate, triphosphate, phosphite, chloride, chlorate, bromide,bromate, iodide, iodate, carbonate or hydrogen carbonate.

To be mentioned as the cation component of the conducting salts that canbe used according to the invention are, inter alia, alkali metal ionssuch as Li⁺, Na⁺, K⁺ or Rb⁺, alkaline earth metal ions such as Mg²⁺,Ca²⁺, Sr²⁺ or Ba²⁺, ammonium ions or phosphonium ions.

To be mentioned with respect to the ammonium ions are quaternaryammonium ions and protonated mono-, di- and triamines.

The examples for quaternary ammonium ions preferentially used accordingto the invention include, inter alia

-   -   symmetric ammonium ions such as tetraalkylammonium preferably        containing C₁-C₄-alkyl, for example methyl, ethyl, n-propyl,        isopropyl, n-butyl, isobutyl, t-butyl, such as        tetramethylammonium, tetraethylammonium, tetrapropylammonium,        tetrabutylammonium or    -   nonsymmetric ammonium ions such as nonsymmetric        tetraalkylammonium preferably containing C₁-C₄-alkyl, for        example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,        t-butyl, such as e.g. methyltributylammonium or    -   ammonium ions containing at least one aryl such as e.g. phenyl        or naphthyl or at least one alkaryl such as e.g. benzyl or at        least one aralkyl and at least one alkyl, preferably        C₁-C₄-alkyl, for example methyl, ethyl, n-propyl, isopropyl,        n-butyl, isobutyl, t-butyl, such as aryltrialkyl such as        benzyltrimethylammonium or benzyltriethylammonium.

According to a particularly preferred embodiment, use is made in themethod according to the invention of at least one conducting salt whichcomprises, as at least one cationic component, a methyltributylammoniumion.

According to a particularly preferred embodiment, the method accordingto the invention makes use of methyltributylammonium methyl sulfate asthe conducting salt.

Conducting salts which can be used in the method according to theinvention are also ionic liquids such as e.g. methylethylimidazoliumchloride or methylbutylimidazolium chloride.

According to a likewise preferred embodiment, the method according tothe invention employs methane sulfonate as the conducting salt.

The cation component of the at least one conducting salt can, accordingto the invention, take the form of protonated or quaternary heterocycliccompounds such as e.g. the imidazolium ion.

Within the scope of an embodiment, preferred inter alia, of the methodaccording to the invention it is possible, via the cationic and/oranionic component of the at least one conducting salt, to introducecompounds into the reaction medium which are employed for establishingthe metal-organic framework material. These compounds are those whichaffect the formation of the structure of the metal-organic frameworkmaterial but which are not present in the resulting framework material,as well as those that are present in the resulting framework material.In particular it is possible, in the method according to the invention,to introduce, via at least one conducting salt, at least one compoundwhich is present in the resulting metal-organic framework material.

Preference is given in this respect, for example, inter alia, totetraalkylammonium carboxylate such as a monotetraalkylammonium salt of1,3,5-benzenetricarboxylic acid. Within the scope of this embodiment itis preferred, inter alia, for 1,3,5-benzenetricarboxylic acid to be usedtogether with tetraalkylammoniumhydroxide in methanol as the solvent.This way of managing the process is claimed to have the advantage, interalia, that tetraalkylammoniumhydroxide is used as an aqueous solution,as a rule, and water thus automatically becomes an essential componentof the reaction medium.

Accordingly, the present invention also describes a method as describedabove wherein at least one compound required for establishing themetal-organic framework material, preferably at least one compoundpresent in the metal-organic framework material to be prepared isintroduced, at least in part, via at least one conducting salt into thereaction system.

Within the scope of an embodiment of the method according to theinvention it is therefore possible for the metal ion, in addition to theat least one anode as the metal ion source, to be introduced via thecationic component of the at least one conducting salt into the reactionmedium. Likewise it is possible to introduce into the reaction medium,via the cationic component of the at least one conducting salt, at leastone metal ion which differs from the at least one metal ion introducedvia anodic oxidation, where this difference can relate to the valency ofthe cation and/or the type of the metal.

Likewise it is possible, within the scope of the method according to theinvention, for salts to be used as conducting salts whose anioncomponent or anion components represents a compound which is used toestablish the metal-organic framework material. In particular it istherefore possible to use conducting salts whose anion components forexample represent the monocarboxylate or dicarboxylate or tricarboxylateor tetracarboxylate or monosulfonate or disulfonate or trisulfonate ortetrasulfonate, preferably a dicarboxylate or tricarboxylate ortetracarboxylate and more preferably the dicarboxylate or tricarboxylateor tetracarboxylate of the preferentially employed aromatic di-, tri- ortetracarboxylic acid.

Accordingly, the present invention also describes a method as describedabove, wherein the at least one conducting salt comprises a salt of theat least one at least bidentate compound.

The present invention further also describes the method as describedabove wherein the at least one conducting salt comprises as the cationcomponent a quaternary ammonium ion and as the anion component acarboxylate of the at least one at least bidentate compound.

The concentration of the at least one conducting salt within the scopeof the method according to the invention is generally in the range offrom 0.01 to 10 wt %, preferably in the range of from 0.05 to 5 wt % andparticularly preferably in the range of from 0.1 to 3 wt %, in each casebased on the sum of the weights of all the conducting salts present inthe reaction system and further based on the total weight of thereaction system without including the anodes and cathodes.

A major advantage of the present method according to the inventionshould therefore be seen in the fact that none of the abovementionedcritical anions such as halides or nitrate, which in the conventionalmethod are introduced via the at least one metal salt into the reactionmedium, is introduced in stoichiometric quantities but only, if at all,in substoichiometric quantities, i.e. essentially in catalyticquantities, via the at least one conducting salt.

If the method is implemented in batch mode, the general procedure isfirst to provide the reaction medium with the starting materials, thento apply current, followed by pumped circulation.

If the method is implemented in continuous mode, the general procedureis to divert a substream from the reaction medium, to isolate thecrystalline, porous, metal-organic framework material present in thesubstream, and to recycle the mother liquor.

A further advantage offered by the method according to the inventioncompared with the prior art methods using metal salts as startingmaterials in the preparation of the porous, metal-organic frameworkmaterials is the fact that according to the invention a higher solidscontent in the reaction medium can be achieved in each synthesis batch,as the solids content is not limited by the amount of starting materialsalt used. This is because the metal cation can be replenished adlibertum via the anode.

The term “solids content” as used within the scope of the presentinvention refers to the amount of separated solid after the reaction,based on the total amount of the reaction batch.

In contrast to the prior art preparation method, in which it isnecessary to dissolve not only the ligand, but also the metal salt, theat least one solvent is completely available, within the scope of themethod according to the invention, for dissolving and/or suspending,preferably for dissolving the ligand.

This applies, in particular, in a continuous-mode variant of the methodaccording to the invention, in which the anode is fed forward to theextent that it is ablated by anodic oxidation. This is effected asdescribed above, for example within the context of a pencil sharpenercell. In analogy to the anode being fed forward, the at least one atleast bidentate compound is replenished. In the process it is thenpossible for the suspension formed, which comprises the metal-organicframework material, to be discharged continuously.

This replenishment of the metal cation via feed-forward of the anode, anexperimentally simple procedure, considerably increases the economicefficiency of the method of preparing the porous, metal-organicframework materials.

Generally, the solids content is at least 0.5 wt %, particularlypreferably in the range of from 0.5 to 50 wt %.

Accordingly, the present invention also relates to a method as describedabove wherein the solids content is in the range of from 0.5 to 50 wt %.

According to an especially preferred embodiment, the method according tothe invention is implemented in such a way as to prevent theredeposition on the cathode of the metal ion liberated by anodicoxidation.

Said redeposition is preferentially prevented, for example, according tothe invention, by employing a cathode which, in a given reaction medium,has a suitable hydrogen overpotential. Such cathodes are, for example,the abovementioned graphite, copper, zinc, tin, manganese, silver, gold,platinum cathodes or cathodes comprising alloys such as steels, bronzesor brass.

The redeposition is further prevented, according to the invention, forexample, by employing in the reaction medium an electrolyte whichpromotes the cathodic formation of hydrogen. In this respect, anelectrolyte is preferred, inter alia, which comprises at least oneprotic solvent. Preferred examples of such solvents have been listedabove, alcohols being particularly preferred, methanol and ethanol beingespecially preferred.

The redeposition is further prevented, according to the invention, forexample, by employing a reaction medium containing at least one compoundwhich leads to cathodic depolarization. A compound leading to cathodicdepolarization is to be understood, within the scope of the presentinvention, as any compound which under given reaction conditions isreduced at the cathode.

Preferred cathodic depolarizers, inter alia, are compounds which arehydrodimerized at the cathode. Particularly preferred in this context,for example, are acrylonitrile, acrylic acid esters and maleic acidesters such as e.g., more preferably, dimethyl maleate.

More preferred as cathodic depolarizers are, inter alia, compoundscomprising at least one carbonyl group which is reduced at the cathode.Examples of such compounds comprising carbonyl groups are e.g. esterssuch as dialkylphthalates and ketones such as acetone.

Preferred cathodic depolarizers are, inter alia, compounds having atleast one nitrogen-oxygen bond, a nitrogen-nitrogen bond and/or anitrogen-carbon bond, which are reduced at the cathode. Examples of suchcompounds are e.g. compounds have a nitro group, an azo group, an azoxygroup, oximes, pyridines, imines, nitriles and/or cyanates.

Within the scope of the method according to the invention it is furtherpossible to combine at least two of the said measures for preventing thecathodic redeposition. It is possible, for example, to use both anelectrolyte which promotes the cathodic formation of hydrogen and to usean electrode having a suitable hydrogen overpotential. Equally it ispossible to use both an electrolyte which promotes the cathodicformation of hydrogen and to add at least one compound which leads tocathodic depolarization. Equally it is possible both to add at least onecompound which leads to cathodic depolarization and to employ a cathodehaving a suitable hydrogen overpotential. Furthermore it is possibleboth to use an electrolyte which promotes the cathodic formation ofhydrogen and to employ an electrode having a suitable hydrogenoverpotential and also to add at least one compound which leads tocathodic depolarization.

Accordingly, the present invention also relates to a method as describedabove wherein the cathodic redeposition of the at least one metal ion isat least partially prevented by at least one of the following measures:

(i) the use of an electrolyte which promotes the cathodic formation ofhydrogen;

(ii) the addition of at least one compound leading to cathodicdepolarization;

(iii) the use of a cathode having a suitable hydrogen overpotential.

Likewise, the present invention therefore also relates to a method asdescribed above wherein the electrolyte according to (i) comprises atleast one protic solvent, particularly an alcohol, more preferablymethanol and/or ethanol.

Likewise, the present invention therefore also relates to a method asdescribed above, wherein the cathodic depolarization is ahydrodimerization, particularly a hydrodimerization of a maleic aciddiester, more preferably of dimethyl maleate.

Particularly preferably, the present invention describes a method asdescribed above wherein, in order to prevent the redeposition, both atleast one protic solvent, preferably an alcohol, more preferablymethanol or ethanol or a mixture of methanol and ethanol, and at leastone compound cathodically capable of hydrodimerization, preferably amaleic acid diester, more preferably a dimethyl maleate, are used.

According to an especially preferred embodiment, the method according tothe invention is operated in recycle mode. This “electrolytic cycle” isto be understood, within the scope of the present invention, to mean anyprocess mode in which at least part of the reaction system contained inthe electrolytic cell is removed from the electrolytic cell, optionallysubjected to at least one intermediate treatment step such as e.g. atleast one thermal treatment or addition and/or separation of at leastone component of the discharged stream and is returned to theelectrolytic cell. Particularly preferably, such an electrolytic cycleis carried out, within the scope of the present invention, incombination with a plate stack cell, a tubular cell or a pencilsharpener cell.

After the preparation has been carried out, the generally crystallineframework material is present in the mother liquor in the form of theprimary crystals.

After the metal-organic framework material has been prepared, theframework material solid is separated from its mother liquor. Thisseparation process can, in principle, be effected via any suitabletechnique. Preferably, separation of the framework material solid isachieved via solid-liquid separation, centrifugation, extraction,filtration, membrane filtration, cross-flow filtration, diafiltration,ultrafiltration, flocculation with the use of flocculation aids such ase.g. nonionic, cationic and/or anionic aids, pH shift by addingadditives such as e.g. salts, acids or bases, flotation, spray-drying,spray granulation or evaporation of the mother liquor at elevatedtemperatures or reduced pressure and concentration of the solid.

The separation can be followed by at least one additional washing step,at least one additional drying step and/or at least one additionalcalcining step.

If the method according to the invention comprises at least onesubsequent washing step, washing is preferably effected using at leastone solvent employed in the synthesis.

If the method according to the invention, if appropriate after at leastone washing step, comprises at least one subsequent drying step, theframework material solid is dried at temperatures generally in the rangeof from 20 to 120° C., preferably in the range of from 40 to 100° C. andparticularly preferably in the range of from 56 to 60° C.

Also preferred is vacuum drying, generally allowing temperatures to bechosen such that the at least one wash medium is removed at leastpartially, preferably essentially in its entirety, from the crystalline,porous, metal-organic framework material while at the same time theframework structure is not destroyed.

The drying time is generally in the range of from 0.1 to 15 h,preferably in the range of from 0.2 to 5 h and especially preferably inthe range of from 0.5 to 1 h.

The if appropriate at least one washing step and if appropriate at leastone drying step can be followed by at least one calcining step, in whichthe temperatures chosen are preferably such that the structure of theframework material is not destroyed.

For example it is possible, particularly by washing and/or drying and/orcalcining, for at least one template compound If appropriate used forthe inventive electrochemical preparation of the framework material tobe removed at least in part and preferably essentially quantitatively.

As well as to the electrochemical preparation method, the presentinvention also relates to the porous, metal-organic framework materialper se prepared via the method as described above.

The crystalline, porous, metal-organic framework material is generallyproduced as a fine powder, the crystals being of a size in the range offrom 0.1 to 100 μm as determined via SEM (Scanning Electron Microscopy).

The pore sizes of the porous, metal-organic framework materials preparedaccording to the invention can be adjusted over wide ranges via the typeand number of the at least bidentate organic compound and/or type and,if appropriate, the oxidation state of the at least one metal ion.

Accordingly it is possible for the framework material prepared accordingto the invention to contain micropores or mesopores or macropores ormicro- and mesopores or micro- and macropores or meso- and macropores ormicro- and meso- and macropores. Especially preferably, the frameworkmaterials prepared according to the invention comprise micropores ormesopores or micro- and mesopores. The term “micropores” as used withinthe scope of the present invention refers to pores having a diameter ofup to 2 nm. The term “mesopores” as used within the scope of the presentinvention refers to pores having a diameter of more than 2 nm up to 50nm. These definitions correspond to the definitions as can be found inPure Appl. Chem. 45 (1976), p. 71 et seq., particularly p. 79. Thepresence of micro- and/or mesopores can be determined via nitrogenadsorption measurements at 77 K in accordance with DIN 66131 and DIN66135 and DIN 66134.

Accordingly, the present invention also describes a framework materialas described above which comprises micropores or mesopores or bothmicro- and mesopores.

The specific surface area of the crystalline, porous, metal-organicframework materials according to the invention as determined via DIN66135 is generally at least 5 m²/g, especially more than 5 m²/g, morepreferably at least 10 m²/g especially more than 10 m²/g, morepreferably at least 50 m²/g, especially more than 50 m²/g, morepreferably at least 100 m²/g, especially more than 100 m²/g, morepreferably at least 250 m²/g, especially more than 250 m²/g, morepreferably at least 500 m²/g, especially more than 500 m²/g, and thespecific surface area can be up to more than 1000 m²/g, such as e.g.more than 2000 m²/g, further e.g. more than 3000 m²/g and especiallye.g. more than 4000 m²/g.

The term “specific surface area” as used within the scope of the presentinvention refers to the surface area as determined in accordance withthe Langmuir model according to DIN 66135 at 77 K.

Accordingly, the present invention also relates to a metal-organicframework material as described above, which has a specific surfacearea, determined in accordance with DIN 66135, of greater than or equalto 250 m²/g.

According to a further embodiment of the method according to theinvention, the porous, metal-organic framework material separated fromthe mother liquor is formed to produce one or more shaped articles.

The possible geometries of these shaped articles are essentially notsubject to any restrictions. The examples to be mentioned include, interalia, pellets such as e.g. disk-shaped pellets, tablets, spheres,granules, extrudates such as e.g. strands, honeycombs, grids or hollowbodies.

Fabrication of these shaped articles is possible, in principle, via anysuitable procedure. Within the scope of the present invention, thefollowing process modes are preferred, inter alia:

-   -   kneading of the framework material on its own or together with        at least one binder and/or at least one pasting agent and/or at        least one template compound to obtain a mixture;    -   shaping the resulting mixture by means of at least one suitable        method such as e.g. extrusion;    -   optional washing and/or drying and/or calcining of the        extrudate;    -   optional conditioning.    -   Applying the framework material to at least one support material        which may or may not be porous. The material obtained can then        be further processed in accordance with the above-described        method to produce a shaped article.    -   Applying the framework material to at least one substrate which        is if appropriate porous.

Kneading and shaping can be effected via any suitable technique, such asdescribed, e.g. in Ullmanns Enzyklopädie der Technischen Chemie,[Ullmann's Encyclopedia of Technical Chemistry], 4th Edition, Vol. 2, p.313 et seq. (1972), which is incorporated by reference.

Preferentially, for example, kneading and/or shaping can be effected bymeans of a piston press, roll press in the presence or absence of atleast one binder material, compounding, pelleting, tableting, extrusion,coextrusion, foaming, spinning, coating, granulation, preferably spraygranulation, spraying, spray-drying or a combination of two or more ofthese methods.

Especially, the method according to the invention involves thepreparation of pellets and/or tablets.

Said kneading and/or shaping can be effected at elevated temperaturessuch as e.g. in the range of from room temperature to 300° C. and/or atelevated pressure such as e.g. in the range of from atmospheric pressureup to a few hundred bar and/or in a protective gas atmosphere such ase.g. in the presence of at least one noble gas, nitrogen or a mixture oftwo or more of these.

Said kneading and/or shaping is effected, according to a furtherembodiment of the method according to the invention, with the additionof at least one binder, where the binder used can in principle be anychemical compound which ensures that the viscosity of the composition tobe kneaded and/or shaped is as desired for kneading and/or shaping.Accordingly, binders for the purpose of the present invention can beeither viscosity-raising or viscosity-lowering compounds.

Examples of binders which are preferred inter alia include aluminumoxide or binders which comprise aluminum oxide, as described e.g. in WO94/29408, silicon dioxide, as described e.g. in EP 0 592 050 A1,mixtures of silicon dioxide and aluminum oxide, as described e.g. in WO94/13584, clay minerals as described e.g. in JP 03-037156 A, e.g.montmorillonite, kaolin, bentonite, hallosite, dickite, nacrite andanauxite, alkoxysilanes as described e.g. in EP 0 102 544 B1, forexample tetraalkoxysilanes such as e.g. tetramethoxysilane,tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, or for exampletrialkoxysilanes such as e.g. trimethoxysilane, triethoxysilane,tripropoxysilane, tributoxysilane, alkoxytitanates, for exampletetraalkoxytitanates such as e.g. tetramethoxytitanate,tetraethoxytitanate, tetrapropoxytitanate, tetrabutoxytitanate or forexample trialkoxytitanate such as e.g. trimethoxytitanate,triethoxytitanate, tripropoxytitanate, tributoxytitanate,alkoxyzirkonates, for example tetraalkoxyzirconates such as e.g.tetramethoxyzirconate, tetraethoxyzirconate, tetrapropoxyzirconate,tetrabutoxyzirconate, or for example trialkoxyzirconate such as e.g.trimethoxyzirconate, triethoxyzirconate, tripropoxyzirconate,tributoxyzirconate, silica sols, amphiphilic substances and/orgraphites. Graphite is especially preferred.

Examples of a viscosity-raising compound which can be used, ifappropriate in addition to the abovementioned compounds, include anorganic compound and/or a hydrophilic polymer such as e.g. cellulose ora cellulose derivative such as e.g. methyl cellulose and/or apolyacrylate and/or a polymethacrylate and/or a poly(vinyl alcohol)and/or a poly(vinylpyrrolidone) and/or a polyisobutene and/or apolytetrahydrofuran.

The pasting agent used can, inter alia, be preferably water or at leastone alcohol such as e.g. a monoalcohol having from 1 to 4 C atoms suchas e.g. methanol, ethanol, n-propanol, isopropanol, 1-butanol,2-butanol, 2-methyl-1-propanol or 2-methyl-2-propanol or a mixture ofwater and at least one of these alcohols or a polyhydric alcohol such ase.g. a glycol, preferably a water-miscible polyhydric alcohol, on itsown or as a mixture with water and/or at least one of the saidmonohydric alcohols.

Further additives which can be used for kneading and/or shaping include,inter alia, amines or amine derivatives such as e.g. tetraalkylammoniumcompounds or aminoalcohols and carbonate-comprising compounds such ase.g. calcium carbonate. Such further additives are described, forexample, in EP 0 389 041 A1, EP 0 200 260 A1 or WO 95/19222, which areincorporated by reference.

The sequence of additives such as template compound, binder, pastingagent, viscosity-raising substance during shaping and kneading is notcritical, in principle.

According to a further preferred embodiment of the method according tothe invention, the shaped article obtained via kneading and/or shapingis subjected to at least one drying operation which in general iscarried out at a temperature in the range of from 25 to 300° C.,preferably in the range of from 50 to 300° C. and particularlypreferably in the range of from 100 to 300° C. Likewise it is possiblefor drying to be carried out at a reduced pressure or under aprotective-gas atmosphere or by spray drying.

According to a particularly preferred embodiment, this drying operationinvolves the at least partial removal, of at least one compound added asan additive, from the shaped article.

According to a further embodiment of the method according to theinvention, the framework material is applied to at least one materialwhich is if appropriate porous, the use of a porous substrate beingpreferred.

Especially preferably, said application is effected via impregnationwith a liquid, steeping in a liquid, spraying, deposition from liquidphase, deposition from the gas phase (vapor deposition), precipitation,coprecipitation, coating.

The substrate used, which is if appropriate porous, is preferablyaluminum oxide, silica gel, silicates, diatomaeous earths, kaolin,magnesium oxide, activated carbon, titanium dioxide and/or zeolites.

If, for example, nonporous substrates are used, it is possible,according to a further embodiment of the method according to theinvention, to apply the porous, metal-organic framework material to anonporous shaped article and thus to produce shell structures as areknown from egg shell catalysts.

Accordingly, the present invention also describes a shaped articlecomprising at least one porous, metal-organic framework material asdescribed above and/or a framework material obtainable via a method asdescribed above.

Obviously it is also possible, within the scope of the method accordingto the invention, for at least one suitable pore former to be addedduring the fabrication of the shaped articles. The pore formers used inthe method according to the invention can include all those compoundswhich provide the finished shaped article with a specific pore size, aspecific pore size distribution and/or specific pore volumes. Preferredpore formers used in the method according to the invention include,inter alia, polymeric vinyl compounds such as e.g. polystyrene,polyacrylates, polymethacrylates, polyolefins, polyamides andpolyesters. Most especially preferred as pore formers are e.g. compoundswhich can be at least partially, preferably essentially entirely removedat the calcining temperatures of the method according to the invention.One example to be mentioned in this context is malonic acid.

The porous, metal-organic framework materials prepared according to theinvention and/or the shaped articles fabricated according to theinvention and comprising at least one porous, metal-organic frameworkmaterial prepared according to the invention can, in principle, be usedin any conceivable manner. Particularly preferred is their use aspigments or as sensors, as electrical conductors or as ion conductors.

Especially preferred in this context are applications which allow thehigh specific surface area of the framework materials to be utilized.

Especially preferred is the use of the framework materials, optionallypresent in a shaped article, for the purification of gases and/orliquids, as catalysts, for absorbing and/or storing and/or dispensingliquids and/or gases.

Accordingly, the present invention also relates to the use of a porous,metal-organic framework material as described above or of a porous,metal-organic framework material obtainable via the above-describedmethod for purifying at least one liquid and/or at least one gas or as astorage medium for at least one liquid and/or at least one gas.

Particularly preferred is the use for storing at least one gas, thegases to be mentioned including, in particular, hydrogen, C₁-C₄hydrocarbons such as e.g. methane, ethane, propane, butane andespecially methane.

A further especially preferred use of the porous, metal-organicframework material according to the invention is the storage of at leastone gas and/or at least one liquid, particularly preferably at least onegas, especially preferably the storage of methane or hydrogen, in avessel at a pressure in the range of from 1 to 750 bar, for examplepreferably in the range of from 1 to 150 bar, more preferably in therange of from 1 to 80 bar, more preferably in the range of from 45 to 80bar and particularly preferably in the range of from 50 to 80 or, forexample, preferably in the range of from 45 to 750 bar, more preferablyin the range of from 45 to 150 bar, more preferably in the range of from50 to 150 bar and particularly preferably in the range of from 50 to 80bar.

Such vessels can, for example, be employed as part of a fuel cell as canbe used, for example, for operating stationary, mobile and/or portableapplications. Such applications include, for example, power stations,motor vehicles, trucks, buses, cableless applications, mobile telephonesor laptops.

At the same time, said vessel can in principle be of any suitablegeometry. Given the low pressures possible according to the invention,even those vessels are preferentially feasible which deviate fromstandard cylindrical geometry and can be variably adapted to particularrequirements, for example the specific spatial stipulations in motorvehicle manufacture. This allows the vessels which can be of variabledesign to be fitted into not otherwise utilizable cavities of a motorvehicle, thus gaining valuable stowage space and useful space.

The following examples and figures are intended to illustrate thepresent invention.

In detail in the figures:

FIG. 1 shows the X-ray diffractograph of Cu-MOF according to example 2.The abscissa represents the 2Θ scale, the Lin (counts) being plotted onthe ordinate;

FIG. 2 shows the X-ray diffractograph of Cu-MOF according to example 3.The abscissa represents the 2Θ scale, the Lin (counts) being plotted onthe ordinate;

FIG. 3 shows the X-ray diffractograph of Cu-MOF according to example 5.The abscissa represents the 2Θ scale, the Lin (counts) being plotted onthe ordinate;

FIG. 4 shows the X-ray diffractograph of Cu-MOF according to example 9.The abscissa represents the 2Θ scale, the Lin (counts) being plotted onthe ordinate;

FIG. 5 shows a comparison of the prior art wherein

— MOF-ST -·-·- EMOF-2 ---- EMOF-1 ········· Tenorite

-   -   and the MOF-ST sample prepared according to the prior art has an        additional maximum at about 8.9798 keV.

EXAMPLES Example 1 Preparation of a Zn-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelzinc electrodes (thickness about 2 mm; facing surface areas each 7.1cm²) spaced 1 cm apart, a mixture of 47.5 g of diethylformamide, 4.0 gof terephthalic acid, 5.0 g of dimethyl maleate and 1.0 g ofmethyltributylammonium methyl sulfate (MTBS) was electrolyzed at 53-57°C. At a constant amperage of 0.2 A, the cell voltage gradually roseduring the electrolysis from 15.8 V to 19.2 V over a period of 3 h. Theend of the electrolysis could be discerned from a further distinctivevoltage rise to above 30 V. It was terminated after 4 h. A dense, whitesuspension had formed which settled rapidly. The resulting precipitatewas filtered off in a nitrogen stream and washed twice with 50 ml ofchloroform. The filter cake was transferred, in a nitrogen atmosphere,to a glass flask and activated in high vacuum (until 5*10⁻⁵ mbar hadbeen reached). Yield: 4.8 g (surface area according to Langmuir inaccordance with DIN 66135: 350 m²/g).

Example 2 Preparation of a Cu-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelcopper electrodes (thickness about 2 mm; facing surface areas each 9.9cm²) spaced 1 cm apart, a mixture of 47.5 g of diethylformamide, 4.0 gof terephthalic acid, 5.0 g of dimethyl maleate and 1.0 g ofmethyltributylammonium methyl sulfate (MTBS) was electrolyzed at 21° C.At a constant amperage of 0.2 A, the cell voltage rose during theelectrolysis from 23.1 V to 33.8 V. The electrolysis was terminatedafter 4 h. A dense, turquoise colored suspension had formed whichsettled rapidly. The resulting precipitate was filtered off in anitrogen stream and washed twice with 50 ml of chloroform. The filtercake was transferred, in a nitrogen atmosphere, to a glass flask andactivated in high vacuum (until 5*10⁻⁵ mbar had been reached). Yield:5.1 g (surface area according to Langmuir in accordance with DIN 66135:256 m²/g).

Example 3 Preparation of a Cu-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelcopper electrodes (thickness about 2 mm; facing surface areas each 9.9cm²) spaced 1 cm apart, a mixture of 47.5 g of diethylformamide, 4.0 gof terephthalic acid, 5.0 g of dimethyl maleate and 1.0 g ofmethyltributylammonium methyl sulfate (MTBS) was electrolyzed at 58-61°C. At a constant amperage of 0.2 A, the cell voltage rose during theelectrolysis from 13.8 V to 18.0 V. The electrolysis was terminatedafter 4 h. A dense, turquoise colored suspension had formed whichsettled rapidly. The resulting precipitate was filtered off in anitrogen stream and washed twice with 50 ml of chloroform. The filtercake was transferred, in a nitrogen atmosphere, to a glass flask andactivated in high vacuum (until 5*10⁻⁵ mbar had been reached). Yield:4.5 g (surface area according to Langmuir in accordance with DIN 66135:477 m²/g).

Example 4 Preparation of a Mg-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelelectrodes (thickness about 2 mm; facing surface areas each 9.9 cm²),the anode being made of magnesium and the cathode being made of copper,spaced 1 cm apart, a mixture of 47.5 g of diethylformamide, 4.0 g ofterephthalic acid, 5.0 g of dimethyl maleate and 1.0 g ofmethyltributylammonium methyl sulfate (MTBS) was electrolyzed at 58-61°C. At a constant amperage of 0.2 A, the cell voltage rose during theelectrolysis from 13.8 V to 18.0 V. The electrolysis was terminatedafter 4 h. A pale gray suspension had formed which settled rapidly. Theresulting precipitate was filtered off in a nitrogen stream and washedtwice with 50 ml of chloroform. The filter cake was transferred, in anitrogen atmosphere, to a glass flask and activated in high vacuum(until 5*10⁻⁵ mbar had been reached). Yield: 3.5 g (surface areaaccording to Langmuir in accordance with DIN 66135: 10.7 m²/g).

Example 5 Preparation of a Cu-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelcopper electrodes (thickness about 2 mm; facing surface areas each 9.9cm²) spaced 1 cm apart, a solution of 50.0 g of ethanol, 5.3 g of1,3,5-benzenetricarboxylic acid and 1.0 g of methyltributylammoniummethyl sulfate (MTBS) was electrolyzed at 53-58° C. At a constantamperage of 0.2 A, the cell voltage during the electrolysis was 18.0 Vto 20 V. The end of the electrolysis could be discerned from a markedvoltage rise to above 30 V. It was terminated after 4 h. A dense,turquoise colored suspension had formed which settled rapidly. Theresulting precipitate was filtered off in a nitrogen stream and washedtwice with 50 ml of chloroform. The filter cake was transferred, in anitrogen atmosphere, to a glass flask and activated in high vacuum(until 5*10⁻⁵ mbar had been reached). Yield: 6.3 g (surface areaaccording to Langmuir in accordance with DIN 66135: 1260 m²/g).

Example 6 Preparation of a Cu-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelcopper electrodes (thickness about 2 mm; facing surface areas each 9.9cm²) spaced 1 cm apart, a mixture of 50.0 g of methanol, 1.0 g of2,2′-bipyridine-5,5′-dicarboxylic acid and 0.3 g ofmethyltributylammonium methyl sulfate (MTBS) was electrolyzed at 51-54°C. At a constant amperage of 0.1 A, the cell voltage during theelectrolysis was a stable 6 V. It was terminated after 1.3 h. A graysuspension had formed which settled rapidly. The supernatant solutionwas colorless. The resulting precipitate was filtered off with suction,washed with methanol a number of times and dried. Yield: 1.4 g. Theprecipitate had an atomic Cu/N/C ratio of 1:2:12.

Example 7 Preparation of a Co-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelcobalt electrodes (thickness about 2 mm; facing surface areas each 9.9cm²) spaced 1 cm apart, a mixture of 50 g of methanol, 4.0 g ofterephthalic acid and 1.0 g of methyltributylammonium methyl sulfate(MTBS) was electrolyzed at 54-65° C. At a constant amperage of 0.2 A,the cell voltage during the electrolysis was 5 V. It was terminatedafter 4 h. A pink suspension had formed which settled rapidly. Theresulting precipitate was filtered off in a nitrogen stream and washedtwice with 50 ml of chloroform. The filter cake was transferred, in anitrogen atmosphere, to a glass flask and activated in high vacuum(until 5*10⁻⁵ mbar had been reached). Yield: 5 g (surface area accordingto Langmuir in accordance with DIN 66135: 7 m²/g). In the course of theelectrolysis, the electrodes had lost 1.19 g, corresponding to anerosion rate of 1.5 F/Mol of Co.

Example 8 Preparation of a Zn-MOF in a Gap Cell

In a N₂-blanketed 100 ml glass cylinder equipped with heating jacket,magnetic stirrer, internal thermometer and fitted with two plan parallelzinc electrodes (thickness about 2 mm; facing surface areas each 0.99cm²) spaced 1 cm apart, a mixture of 47.5 g of diethylformamide, 4.8 gof 2,5-dihydroxyterephthalic acid, 5.0 g of dimethyl maleate and 1.0 gof methyltributylammonium methyl sulfate (MTBS) was electrolyzed at52-61° C. At a constant amperage of 0.2 A, the cell voltage graduallyrose during the electrolysis from 12.5 V to 37.0 V over a period of 3 h.It was terminated after 4 h. A dense, yellow/beige suspension had formedwhich settled rapidly. The resulting precipitate was filtered off in anitrogen stream and washed twice with 50 ml of chloroform. The filtercake was transferred, in a nitrogen atmosphere, to a glass flask andactivated in high vacuum (until 5*10⁻⁵ mbar had been reached). Yield:4.3 g (surface area according to Langmuir in accordance with DIN 66135:21 m²/g).

Example 9 Preparation of a Cu-MOF in a Plate Stack Cell

Electrolysis was carried out in an electrolytic circuit consisting of acirculating pump, a glass cooler for regulating the temperature of theelectrolyte, an off-gas condenser, measuring devices for measuring theflow rate, the cell voltage, the current density and the temperature,and of a plate stack cell. The plate stack cell comprised five roundcopper disks having an area on each side of 61.9 cm² and a thickness of5 mm. The disks having a central circular hole with a diameter of 1.5 cmwere arranged to form a stack. Spacers separated each electrode from theadjacent electrodes by a 1 mm gap. Cathodic contact was made with thebottom electrode and anodic contact with the top electrode. The threecentral electrodes each had a cathodic and an anodic side (bipolarconfiguration). Via the cell bottom plate, the electrolyte was passedthrough the central cylindrical holes of the plates, flowing through thegaps. Via a glass cap fixed to the bottom plate, the electrolyte wasdischarged into the cell circuit and anodic contact was effected. Theinstallation had been inerted with nitrogen.

An electrolyte comprising 1075.7 g of methanol, 83.3 g of1,2,3-benzenetricarboxylic acid and 21 g of MTBS was recirculated inthis cell circuit (130 l/h). Electrolysis was carried out at an amperageof 1.3 A and a cell voltage of from 12.6 to 19.1 V and a temperature of20-23° C. for two and a half hours. The precipitate was filtered off andwashed twice with 50 ml of cold methanol. The pale blue precipitate wasactivated overnight at 120° C., its color changing to dark blue in theprocess. Yield 43.6 g (surface area according to Langmuir in accordancewith DIN 66135: 1649 m²/g).

Example 10 Preparation of a Cu-MOF in a Plate Stack Cell

An experiment analogous to example 9 in ethanol as the solvent affordeda product having a surface area of 1585 m²/g according to Langmuir inaccordance with DIN 66135 and a yield of 15.5 g.

Example 11 Preparation of a Cu-MOF in a Tubular Cell

The cell circuit was charged with the electrolyte comprising 144.8 g of1,3,5-benzenetricarboxylic acid, 38 g of MTBS and 1867.2 g of methanol.The cell circuit consisted of a tubular cell, a glass cooler, acentrifugal pump and a separation vessel underneath the cell. The pumpconveyed the electrolyte and the suspension formed in the circuit, themain quantity of the Cu-MOF formed being collected in the separationvessel. The separation vessel consisted of a glass beaker having avolume of 500 ml with a drain at the bottom. The tubular cell consistedof an alloy steel tube (length: 55 cm, internal diameter: 4.1 cm) havinga polypropylene cap and a polypropylene bottom. Cap and bottom hadorifices for supplying and discharging the electrolyte circulating inthe cell circuit. The cap had a screw-sealable port from which thecopper anode projected gas tightly. The bottom had a circular recess(diameter corresponding to the anode rod) with a thickness of 3 mm, inwhich the anode was seated. The cap port and the bottom recess werearranged concentrically with the cross section of the steel cathode,thereby ensuring that the spacing between cathode and anode washomogeneous all round. The copper anode consisted of a copper rod havinga length of 100 cm and a diameter of 4 cm, which was tapered in thevicinity of the steel cathode. There it had a diameter of 3.7 cm,corresponding to an active surface area of 639 cm².

At an amperage of 14.5 A and a cell voltage of from 5.6 to 5.9 V, theexperiment was continued until a current consumption of 1.5 F/(Mol ofbenzenetricarboxylic acid) had been reached. Then, the circulation wascontinued at zero current for a few hours, a large fraction of the MOFsuspension being collected in the separation vessel in the process. Thusit was possible to run a number of batches of fresh electrolysis chargesone after the other without solids accumulating in the cell or in thecell circuit.

Work-up of these MOF outputs resulted, on average, in 105 to 115 g ofsolids per batch having surface areas, determined according to Langmuirin accordance with DIN 66135, ranging from 1300 to 1500 m²/g.

Example 12 Preparation of the Tetrapropylammonium Salt of1,3,5-benzenetricarboxylic Acid

A methanolic solution of 0.35 Mol of 1,3,5-benzenetricarboxylic acid perkg of methanol (7.2 wt %), upon addition of 0.035 Mol oftetrapropylammonium hydroxide, 50% strength in H₂O, attained a specificconductivity of 1.0 mS/cm. 10 Mol % of the 1,3,5-benzenetricarboxylicacid had been converted into the monosalt in this solution. The solutioncontained 7.1 g of water, corresponding to 0.7 wt %.

Example 13 Comparison of Cu-MOFs Prepared According to the PresentInvention with Conventionally Prepared Copper-MOFs

Two electrochemically prepared Cu-MOFs (EMOF-1 and EMOF-2) areinvestigated by X-ray absorption spectroscopy and compared with a Cu-MOFprepared according to the prior art (MOF-ST).

EMOF-ST is prepared as follows:

Material used Molar Computed Experimental 1) 1,3,5-Benzenetricarboxylicacid 0.116 mol 24.4 g 24.4 g 2) Ethanol  2.13 mol 98.5 g 98.5 g 3)Copper(II) nitrate*2.5 water 0.233 mol 54.3 g 54.3 g 4) Deionized water 6.94 mol 125.0 g  125.0 g 

In each of two autoclave beakers 12.2 g of benzenetricarboxylic acid aresuspended in 49.3 g of ethanol by stirring. In each of 2 glass beakers27.2 g of copper nitrate are dissolved in 62.5 g of water. The coppernitrate solution is then filled into the glass beakers, and a light bluegel forms. It is stirred for 30 min and then the autoclave beakers aresealed.

The crystallization takes place at 110° C. over 18 h.

The precipitate is filtered off and washed 2 times with water. Thefilter cake is dried at 110° C.

Analysis:

Langmuir surface area: 1316 m²/g measured with N₂/77K

Chemical analysis:

Cu: 32%

N: 1.1%

In the case of EMOF-1, 1788.3 g of methanol, 70.0 g of1,3,5-benzenetricarboxylic acid, 28.6 g of MTBS (60% in methanol) andalso a CU electrode are used and the EMOF-1 is obtained similarly to theprevious examples.

Langmuir surface area: 1766 m²/g measured with N₂/77K.

Thus, MOF-ST and EMOF-1 are directly comparable. It emerges that EMOF-1has a larger active surface area.

EMOF-2 is prepared similarly to EMOF-1, except that isophthalic acid isused. The hereinbelow more particularly described X-rayabsorption-spectroscopic investigation shows that the spectra of theEMOFs have comparable characteristics in the spectra and differ greatlyfrom MOF-ST in that respect.

Sample preparation and the subsequent measurements for X-ray absorptionspectroscopy are carried out under the same conditions for all Cu-MOFs.

By way of sample pretreatment, all the samples are alluviated withethanol onto polyethylene compacts 13 mm in diameter. To stabilize thesamples on the PE compacts, these have been packaged in adhesive tape.The measurements of the X-ray absorption spectra were carried out on theE4 beamline of the HASYLAB at DESY. This instrument is equipped with anSi(111) double crystal monochromator and a focusing mirror with goldcoating. To further suppress the higher harmonics, a gold-coated planemirror is used. An additional measurement is carried out at 60% of themaximum intensity of the Bragg peak using a piezo element with feedbackcontrol. The following argon pressures are set for the measurement atthe Cu K edge: 1st ionization chamber 70 mbar, 2nd ionization chamber550 mbar and 3rd ionization chamber 800 mbar. This correspondsrespectively to absorptions of 10% in the first ionization chamber, of50% in the second ionization chamber and of almost 100% in the thirdionization chamber. A copper foil is measured between the second andthird ionization chambers as a reference to calibrate the energy scale.

The measuring programs for the copper edge are:

Energy/eV Step size/eV Measuring time/sec Edge position x 8820 10 0.58940 0.5 0.5 9010 0.5 0.5 8979 0.9 10 000  

From the energy for which an edge position is reported, the measurementis carried out in equidistant steps in the k-space using a waiting ofthe measuring time per step of k^(x). The sample spectra were measuredrepeatedly, as were the reference samples.

Data evaluation was carried out using WinXAS 3.1 software (Ressler T.,J. Synchrotron Radiat., 5 (1998), 118). Data reduction is effected usingstandard methods. Energy calibration utilize the E₀ of the referencefoils which are measured simultaneously at each spectrum. For the XANESrange of the copper samples of interest here, polynomials of first orderare utilized for the preedges (8.84 keV-8.94 keV) and of 2nd order forthe EXAFS range (9.16 keV-9.98 keV) to deduct the background.Normalization is on the edge lift. Converting into the k-space utilizesthe 2nd turning point on the edge of the sample spectrum. The μ0adaptation is effected using a spline function (spline7) in the range of1.59 k-13.1 k.

A comparison with the model of tenorite in the space group Cc by meansof the EXAFS and the absence of a preedge peak show that the copper hasa fourfold planar coordination in all samples. A comparison of the firstderivatives of the edges of the samples, however, shows that the MOF-STsample prepared according to the prior art has an additional maximum atabout 8.9798 keV. This is depicted in FIG. 5. The curves are assigned asfollows:

MOF-ST

EMOF-2

EMOF-1

Tenorite

This maximum, which corresponds to a turning point in the originalabsorption spectrum, is not present in the Cu-MOF prepared according tothe present invention. A comparison of the sample spectra with that oftenorite further reveals that, owing to the energetically identicalpositions of the edge structures, the copper is present in a divalentstate in the samples investigated. It cannot be ruled out that theMOF-ST sample has a somewhat lower average oxidation state due to theadditional turning point on the edge.

A comparison of the X-ray absorption spectra of copper-MOFs producedaccording to the present invention compared with those producedaccording to the prior art show distinct differences, so that the MOFsproduced according to the present invention are new entities comparedwith the MOFs produced according to the prior art.

1. A crystalline, porous, metal-organic framework material comprising atleast one at least bidentate organic compound coordinately bound to atleast one metal ion, wherein said framework material is obtained by aprocess comprising electrochemically preparing the framework material ina reaction medium comprising said at least bidentate organic compound,wherein said at least one metal ion is provided in the reaction mediumby the oxidation of at least one anode comprising the correspondingmetal.
 2. The framework material according to claim 1, wherein the atleast one at least bidentate organic compound is selected from the groupconsisting of dicarboxylic acid, tricarboxylic acid and tetracarboxylicacid.
 3. The framework material according to claim 1, wherein theframework material has a specific surface area, determined in accordancewith DIN 66135, of greater than or equal to 5 m²/g.
 4. The frameworkmaterial according to claim 1, wherein, during the process, cathodicredeposition of the at least one metal ion is partially prevented by thepresence of at least one of the following: (i) an electrolyte whichpromotes the cathodic formation of hydrogen; (ii) at least one compoundleading to cathodic depolarization; and (iii) a cathode having asuitable hydrogen overpotential.
 5. The framework material according toclaim 4, wherein the electrolyte comprises at least one protic solvent.6. The framework material according to claim 4, wherein the cathodicdepolarization is a hydrodimerization.
 7. The framework materialaccording to claim 1, wherein the process is implemented in an undividedelectrolytic cell.
 8. The framework material according to claim 1,wherein the process is implemented in a gap cell or plate stack cell. 9.The framework material according to claim 8, wherein the gap cell orplate stack cell is connected for bipolar operation.
 10. The frameworkmaterial according to claim 1, wherein the reaction medium comprisesmethanol, ethanol, dimethylformamide, diethylformamide or a mixture oftwo or more of these.
 11. The framework material according to claim 1,wherein the metal ion source is an anode comprising at least one metalselected from the group consisting of copper, iron and zinc.
 12. Theframework material according to claim 1, wherein the at least bidentateorganic compound is an aromatic di, tri- or tetracarboxylic acid. 13.The framework material according to claim 1, wherein the reaction mediumcomprises at least one conducting salt.
 14. The framework materialaccording to claim 13, wherein the at least one conducting saltcomprises as the cation component a quaternary ammonium ion andcomprises as the anion component an alkoxy sulfate.
 15. The frameworkmaterial according to claim 1, wherein the solids content is in therange of greater than or equal to 0.5 wt %.
 16. A crystalline, porous,metal-organic framework material comprising at least one at leastbidentate organic compound coordinately bound to at least one metal ion,wherein said material is obtained by a process comprisingelectrochemically preparing the framework material in a reaction mediumcomprising said at least bidentate organic compound, wherein said atleast one metal ion is provided in the reaction medium by the oxidationof at least one anode comprising the corresponding metal, whichcomprises partially preventing the cathodic redeposition of the at leastone metal ion by the presence of at least one of the following: (i) anelectrolyte which promotes the cathodic formation of hydrogen; (ii) atleast one compound leading to cathodic depolarization; and (iii) acathode having a suitable hydrogen overpotential.
 17. A storage mediumfor at least one liquid and/or at least one gas comprising the frameworkmaterial according to claim
 1. 18. A catalyst comprising the frameworkmaterial according to claim
 1. 19. A storage medium for at least oneliquid and/or at least one gas comprising the framework materialaccording to claim
 16. 20. A catalyst comprising the framework materialaccording to claim
 16. 21. A pigment comprising the framework materialaccording to claim
 1. 22. A sensor comprising the framework materialaccording to claim
 1. 23. An electrical conductor comprising theframework material according to claim
 1. 24. An ion conductor comprisingthe framework material according to claim
 1. 25. A pigment comprisingthe framework material according to claim
 16. 26. A sensor comprisingthe framework material according to claim
 16. 27. An electricalconductor comprising the framework material according to claim
 16. 28.An ion conductor comprising the framework material according to claim16.